docs: def _start_if_ready(self, task_name):
          """ Start this task if all its dependencies finished successfully. """
          logger.debug('Job {0} running _start_if_ready for task {1}'.format(self.name, task_name))
          task = self.tasks[task_name]
          dependencies = self._dependencies(task_name, self.snapshot)
          for dependency in dependencies:
              if self.run_log['tasks'].get(dependency, {}).get('success', False) == True:
                  continue
              return
          self._put_task_in_run_log(task_name)
          task.start()